PP,PE,PVC,PET,ABS,PPR for Plastic Extruder Machine Conical Twin Screw and Barrel material: bimetallic layer PP,PE,PVC,PET,ABS,PPR ... for Plastic Extruder Machine Conical Twin Screw and Barrel Zhejiang ... screw's ridge,and uses different alloy and welding methods for the screw of different functions.Materials38CrMoAlA (JIS SACM645)SKD61 . ...